I. Field of the Invention
The present invention relates to a medical container stopper which hermetically seals the opening of a medical container.
II. Description of the Prior Art
In order to maintain a given internal negative pressure or to seal the contents from ambient atmosphere, a stopper hermetically seals the opening of a hard medical container such as a vacuum blood collecting tube or an infusion solution bottle. Vulcanized butyl rubber is generally used for a stopper for hermetically sealing a medical container of this type. Vulcanized butyl rubber provides an excellent hermetic seal due to its rubber-like elasticity.
However, additives such as sulfur or a vulcanization accelerator contained in the vulcanized butyl rubber may elute into the blood inside a medical container, thus impairing blood analysis. The problem of elution of the additives is also encountered in the case of sealing infusion bottles. In order to counteract this problem, the surface of a rubber stopper which will be brought into contact with an infusion solution is conventionally coated with a plastic so as to prevent the additives contained in the rubber from eluting into the infusion solution during autoclave sterilization.
In addition to this problem, when a conventional vulcanized butyl rubber stopper comes into contact with blood, blood clots are deposited on the stopper, and this also adversely affects the analysis and test reliability.